feat: migrate InfluxDB and Grafana from digital-twin/ to smart-city/ stack

- docker-compose.influxdb.yml: InfluxDB v2 on smartcity-shared + traefik-public
- docker-compose.grafana.yml: Grafana 10.2 on smartcity-shared + traefik-public
- grafana/provisioning/: dashboards + datasources updated for smart-city
- pulsar/docker-compose.yml: added smartcity-shared network for simulator access

Services migrated (preserving existing volumes):
  - digital-twin-influxdb → smart-city-influxdb
  - digital-twin-grafana  → smart-city-grafana

Traefik routes updated:
  - influxdb.digitribe.fr → smart-city-influxdb:8086
  - grafana.digitribe.fr  → smart-city-grafana:3000

docker-compose.influxdb.yml

@@ -0,0 +1,38 @@
+# InfluxDB v2 - Time-series database for Smart City IoT analytics
+# Usage: docker compose -f docker-compose.influxdb.yml up -d
+
+networks:
+  smartcity-shared:
+    external: true
+  traefik-public:
+    external: true
+
+volumes:
+  influxdb_data:
+    external: false
+    name: digital-twin_influxdb_data
+
+services:
+  influxdb:
+    image: influxdb:2.7-alpine
+    container_name: smart-city-influxdb
+    networks:
+      - smartcity-shared
+      - traefik-public
+    ports:
+      - "8086:8086"
+    environment:
+      - DOCKER_INFLUXDB_INIT_MODE=setup
+      - DOCKER_INFLUXDB_INIT_USERNAME=admin
+      - DOCKER_INFLUXDB_INIT_PASSWORD=admin1234
+      - DOCKER_INFLUXDB_INIT_ORG=digitribe
+      - DOCKER_INFLUXDB_INIT_BUCKET=iot_data
+      - DOCKER_INFLUXDB_INIT_ADMIN_TOKEN=my-super-secret-admin-token
+    volumes:
+      - influxdb_data:/var/lib/influxdb2
+    restart: unless-stopped
+    healthcheck:
+      test: ["CMD", "influx", "ping"]
+      interval: 30s
+      timeout: 10s
+      retries: 5